Servlet 获取的随机图片验证码制作

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Random;

import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
*  获取随机验证码（图片）,防止恶意访问
*  @author lu
*  @version 1.0
*/
public class ImageServlet extends HttpServlet {
private static final long serialVersionUID = 4172288020211199830L;
public static final int WIDTH = 190;
public static final int HEIGHT = 50;
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("image/jpeg");
BufferedImage image = new BufferedImage(WIDTH,HEIGHT,BufferedImage.TYPE_INT_RGB);
Graphics g= image.getGraphics();
setBackGroud(g);
setBorder(g);
drawRandomLine(g);
String random=drawRandomNum((Graphics2D)g);
request.getSession().setAttribute("checkCode",random);
//控制浏览器不缓存验证码
response.setDateHeader("expries",-1);
response.setHeader("Cache-Control","no-cache");
response.setHeader("Prama","no-cache");
ImageIO.write(image,"jpg", response.getOutputStream());
}
//设置随机字符
private String drawRandomNum(Graphics2D g) {
g.setColor(Color.WHITE);
g.setFont(new Font("楷体",Font.BOLD,30));
String base="\u7684\u4e00\u4e86\u662f\u66211\u4e0d\u5728\u4eba\u4eec\u8981\u4e0b\u770b\u5929\u65f6\u8fc7\u41fa" +
"\u751f\u540c\u8001\u4e2d\u5341\u4ece\u81ea\u9762";
StringBuffer sb = new StringBuffer();
int x=20;
for(int i=0;i<=3;i++) {
int degree = new Random().nextInt()%30;
String ch = base.charAt(new Random().nextInt(base.length()))+"";
sb.append(ch);
g.rotate(degree*Math.PI/180,x,35);
g.drawString(ch,x,35);
g.rotate(-degree*Math.PI/180,x,35);
x+=40;
}
return sb.toString();
}
//设置干扰线
private void drawRandomLine(Graphics g) {
g.setColor(Color.WHITE);
for(int i=0;i<5;i++) {
int x1=new Random().nextInt(WIDTH);
int y1=new Random().nextInt(HEIGHT);
int x2=new Random().nextInt(WIDTH);
int y2=new Random().nextInt(HEIGHT);
g.drawLine(x1, y1, x2, y2);
}
}
//设置背景
private void setBorder(Graphics g) {
g.setColor(Color.BLACK);
g.fillRect(2, 2, WIDTH-4, HEIGHT-4);
}
//设置边框
private void setBackGroud(Graphics g) {
g.setColor(Color.GRAY);
g.fillRect(0, 0, WIDTH, HEIGHT);
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doGet(request,response);
}
}